According to the General Requirements for Equipment Reliability Work (GJB450A), reliability testing is divided into six work items.

In addition to the reliability testing work items specified in GJB 450A, from the current trend of development and application of reliability testing technology, reliability development testing includes reliability simulation testing, reliability measurement testing, and reliability baseline growth testing. Reliability simulation testing is the use of digital prototypes for modeling and simulation, analyzing the thermal and vibration stresses of products, and predicting faults using failure physics methods. In the absence of reliability index requirements, conduct reliability testing to understand the reliability level of the product. The reliability growth test is a method of promoting product reliability growth by applying ultimate stress to more fully expose problems and make improvements. It does not evaluate the level of product reliability, but focuses on problem discovery and implementation of improvements.

Environmental Stress Screening (ESS) test is a testing method that simulates the use of products under extreme environmental conditions to detect potential defects in product design and manufacturing processes. It applies stress (such as temperature cycling, vibration, etc.) to quickly expose early potential faults, thereby improving the reliability and stability of the product.
1、 Purpose of ESS test
1. Early fault detection: In the early stages of a product, potential design, material, or manufacturing process defects are identified through accelerated testing to avoid product failures in actual use.
2. Reliability improvement: By eliminating early faulty products, the overall reliability of batches of products is improved, reducing maintenance and repair costs in the later stage.
3. Design verification: Verify whether the performance of the product under extreme environmental conditions meets the design requirements, ensuring that it can work properly in real usage environments.
4. Screening for manufacturing defects: Helps identify potential manufacturing process defects in the production process and adjust the process flow in a timely manner.
2、 At what stage should we conduct ESS testing
Environmental stress screening is generally carried out in the early stages of product manufacturing, especially before the product is officially shipped. Its common application stages include:
1. Prototype stage: After the prototype design of the product is completed, environmental stress screening tests are conducted to evaluate whether its design can cope with extreme environments.
2. Pre mass production stage: Before mass production of the product, ESS is used to screen for potential defects that may be introduced into the production line, ensuring product quality stability.
3. Production line testing: Some products also undergo ESS screening during production line testing to ensure that every product leaving the factory undergoes high-intensity testing and eliminates possible early failures.
Common types of ESS stress
Temperature cycling: Simulating the behavior of a product at extreme temperatures by exposing it to rapid changes between high and low temperatures.
Vibration testing: Apply mechanical vibrations of different frequencies and amplitudes to simulate the impact and vibration environment that the product may encounter during transportation and use.
Humidity testing: Testing in high humidity environments to evaluate the moisture resistance of products.
Electrical stress: Apply additional electrical loads to electrical components and test their performance under overload conditions.
Overall, ESS testing is a key means of enhancing electronic equipment, mechanical equipment, and other high reliability products, ensuring that they can withstand extreme environmental tests before delivery.

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